Vagus %28x%29 Cranial Nerve

8/4/2019 Vagus %28x%29 Cranial Nerve

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Mixed nerve, with

parasympatheticfibers.

Extensive course

Majorparasympathetic

supply to thoracic

and abdominal

viscera.



Nerve of 4th & 6th

pharyngeal arches

Superior laryngealbranch supplies

4th

pharyngealarch structures

Recurrentlaryngeal nerve

supplies 6th

pharyngeal archderivatives



Main motor: Nucleusambiguus : long nucleus,

lies in medulla, sendingmotor fibers in 9th, 10th

& cranial root of 11th

nerves to innervatemuscles of pharynx(exceptstylopharyngeus) &larynx, derived from3,4& 6 pharyngeal

arches. Also suppliesskeletal muscles of upper oesophagus & softpalate (except tensor

veli palatini)



Dorsal motor

nucleus of vagus: lies in the rostral

Medulla Oblongata,

gives preganglionicparasympatheticfibers via vagusnerve to innervate

thoracic & abdominalviscera (cardiacmuscle & smoothmuscle (bronchi &

gut)



Nucleus solitariuslocated in upper

Medulla Oblongata,receives afferentsfrom heart & thoracoabdominal viscera for

reflex activitiesTaste fibers fromepiglottis

Fibers of general

sensation from partsof pharynx & larynxmay go to sensorynucleus of trigeminal

nerve



Postero-lateralsulcus(between olive& inferior

cerebellarpeduncle),between IX andXI, in a series

of rootlets



Jugular foramen

Before and afterforamen, there issmall superior, and acylindrical inferior

ganglion.Superior (jugular)

ganglion has cellbodies of meningeal

& auricular branches Inferior (nodose)

ganglion lodges cellbodies of all other

sensory fibers



Medulla post cranial fossa Exit (jugularforamen)

Superior ganglion

Inferior ganglion

+

cranial root of XI

right

descends

left



Descends in the

neck in carotid

sheath between

internal (or common)

carotid artery andinternal jugular vein



Enters thoracic inlet on right

side of trachea

Travels downward posteriorto right brachiocephalic veinand superior vena cava

Forms posterior esophagealplexus

Forms posterior vagal trunkat esophageal hiatus where

it leaves thorax and passes

into abdominal cavity, then

divides into posterior gastric

and celiac branches



Enters thoracic inlet between left

common carotid & left subclavian

arteries

Crosses aortic arch where left

recurrent laryngeal nerve branches

off Forms anterior esophageal plexus

Forms anterior vagal trunk at

esophageal hiatus where it leavesthorax and passes into abdominal

cavity , then divides into anterior

gastric and hepatic branches



In the neck: a. meningealb. auricular

c. pharyngeald. branches to carotid bodye. superior laryngealf. recurrent laryngeal (right)g. cardiac

In the thorax:a. recurrent laryngeal (left)b. pulmonaryc. oesophageal

In the abdomen: a. gastric

b. coeliac

c. hepatic

d. renal



Meningeal: arises from

superior vagal ganglion,

passes through jugularforamen- infra-tentorial

dura in posterior cranialfossa

Auricular: arises from SVG& runs b/w tympanic &

mastoid parts of Temporal

bone- PI quadrant of Tympanic membrane,external auditory meatus& corresponding skin

behind auricle



Pharyngeal branch:arises from inferior

vagal ganglion,contains fibersfrom XI nerve –

pharyngeal plexus,

supplies all themuscles of pharynx(except,stylopharyngeus) &

soft palate (except,tensor veli palitini)

Carotid body

branches



Superior laryngealnerve: passes down side

of pharynx and given rise

to

Internal branch

(sensory) piercesthyrohyoid membraneto innervate mucousmembrane of larynx

upto vocal cords External branch

(motor) innervates

cricothyroid muscle



Cervical cardiac

branches :

terminate in

cardiac plexus



Recurrent laryngeal

nerves

Right one hooks

around right

subclavian artery, left

one hooks aroundLigamentum

arteriosum/ aortic

arch Both ascend in tracheo-

esophageal groove to

reach the larynx



Nerves enter larynx,

divide into 2 or more

branches, anterior

branch motor, called

inferior laryngeal

nerve

Innervations:

laryngeal mucosa

below vocal cords ,all laryngeal muscles

except cricothyroid



Bronchial and

esophageal branches:terminate inpulmonary &oesophageal plexus



Anterior and posteriorgastric branches

Run close to lessercurvature andinnervate anterior andposterior surfaces of

stomach, as far aspyloric antrum



Hepatic branches:join

hepatic plexusand then supply liverand gallbladder

Celiac branches:send branches toceliac plexus,distributed with

sympathetic fibers toliver, pancreas,spleen, kidneys,intestine as far asleft colic flexure



Unilateral lesion of vagus is followed by

ipsilateral paralysis of the soft palate,pharynx and larynx, leading to

hoarseness of voice, dyspnoea and

dysphagia.

During phonation, soft palate is raisedon the normal side & uvula is deviatedto normal side.

Loss of gag reflex, cough reflex, carotidsinus reflex on the effected side.

Bilateral lesions are fatal



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Vagus %28x%29 Cranial Nerve